The growth and nutrient uptake of winter wheat

Summary Measurements with an ion selective electrode under winter wheat and in adjacent fallow soil, from April to July 1976, showed that nitrate concentrations were high in the 0–25 cm zone and correspondingly lower at 50 cm, because of the extreme drying conditions. Maximum differences in nitrate concentrations between cropped and fallow soil occurred at Feekes' stages 6, 10, and 11.1 indicating periods of maximum uptake by the crop (cf Ref.⁴).Dry matter weight of wheat, sampled biweekly, was maximum 15 days before maturity. The foliage senesced and lost weight from Feekes' stage 10.1 onwards. Nutrient concentrations in the foliage decreased from Feekes' stage 4, but N, P and Mg concentrations in the ears increased during Feekes' stage 11. N, P and Mg accumulated in the ears at the expense of the foliage during stage 11, maximum uptake occurring at stages 11.3, 11.1 and 11.2 respectively. In contrast, K and Ca uptake ceased at stages 10.1 and 10.5 respectively and then both were lost from the foliage in heavy showers.Rates of N uptake and soil nitrate depletion correlated significantly, enabling N uptake to be deduced approximately from thesein situ soil nitrate measurements.     

多效抗旱驱鼠剂对田间小麦促长增产效果研究

通过多效抗旱驱鼠剂浸种与拌种的田间试验,对小麦12个生长和产量构成因素进行了测定与多元统计分析。结果表明,RPA浓度是决定促长与增产效果的关键。药剂A的700倍水溶液浸种或30-50倍液拌种对苗期促长作用最好;与对照相比,除B的700倍水溶液浸种处理小麦种子,小麦产量比对照降低2.79%,其它处理均有增产作用,增产率为4.79%-98.67%。其中以药剂A的70倍水溶液拌种和C的600倍液浸种,增产效果最为显著,增产幅度达98.49%-98.67%;对11个影响产量因子的通径分析表明,单位面积的有效穗数是决定产量增长率的首要因素。     

Root growth and water uptake in winter wheat under deficit irrigation

Root growth is critical for crops to use soil water under water-limited conditions. A field study was conducted to investigate the effect of available soil water on root and shoot growth, and root water uptake in winter wheat (Triticum aestivum L.) under deficit irrigation in a semi-arid environment. Treatments consisted of rainfed, deficit irrigation at different developmental stages, and adequate irrigation. The rainfed plots had the lowest shoot dry weight because available soil water decreased rapidly from booting to late grain filling. For the deficit-irrigation treatments, crops that received irrigation at jointing and booting had higher shoot dry weight than those that received irrigation at anthesis and middle grain filling. Rapid root growth occurred in both rainfed and irrigated crops from floral initiation to anthesis, and maximum rooting depth occurred by booting. Root length density and dry weight decreased after anthesis. From floral initiation to booting, root length density and growth rate were higher in rainfed than in irrigated crops. However, root length density and growth rate were lower in rainfed than in irrigated crops from booting to anthesis. As a result, the difference in root length density between rainfed and irrigated treatments was small during grain filling. The root growth and water use below 1.4 m were limited by a caliche (45% CaCO₃) layer at about 1.4 m profile. The mean water uptake rate decreased as available soil water decreased. During grain filling, root water uptake was higher from the irrigated crops than from the rainfed. Irrigation from jointing to anthesis increased seasonal evapotranspiration, grain yield, harvest index and water-use efficiency based on yield (WUE), but did not affect water-use efficiency based on aboveground biomass. There was no significant difference in WUE among irrigation treatments except one-irrigation at middle grain filling. Due to a relatively deep root system in rainfed crops, the higher grain yield and WUE in irrigated crops compared to rainfed crops was not a result of rooting depth or root length density, but increased harvest index, and higher water uptake rate during grain filling.     

夜间增温对冬小麦根系生长和土壤养分有效性的影响

气候变暖存在明显的昼夜不对称性,夜间气温升高幅度显著高于白天.本研究采用夜间被动式增温系统,于2009-2010年在我国冬小麦主产区（石家庄、徐州、许昌和镇江）进行全生育期田间增温试验,研究了土壤pH值、速效养分和抽穗期冬小麦根系对夜间增温的响应.结果表明： 与不增温对照相比,夜间增温显著降低了土壤pH值和速效养分含量,并在一定程度上提高了根系干质量和根冠比.冬小麦整个生育期,夜间增温分别使石家庄、徐州、许昌和镇江试验点土壤pH值平均降低0.4%、0.4%、0.7%和0.9%,碱解氮含量平均降低8.1%、8.1%、7.1%和6.0%,速效磷含量平均降低15.7%、12.1%、19.6%和25.8%;速效钾含量平均降低11.5%、7.6%、7.6%和10.1%.增温处理下,石家庄、徐州和镇江试验点抽穗期冬小麦根系干质量分别平均增加31.5%、27.0%和14.5%;石家庄、许昌和镇江试验点抽穗期冬小麦根冠比分别平均提高23.8%、13.7%和9.7%.夜间增温可能通过改变土壤化学特性影响土壤养分供应和冬小麦生长     

Interactive effects of soil temperature, atmospheric carbon dioxide and soil N on root development, biomass and nutrient uptake of winter wheat during vegetative growth

Nutrient requirements for plant growth are expected to rise in response to the predicted changes in CO(2) and temperature. In this context, little attention has been paid to the effects of soil temperature, which limits plant growth at early stages in temperate regions. A factorial growth-room experiment was conducted with winter wheat, varying soil temperature (10 degrees C and 15 degrees C), atmospheric CO(2) concentration (360 and 700 ppm), and N supply (low and high). The hypothesis was that soil temperature would modify root development, biomass allocation and nutrient uptake during vegetative growth and that its effects would interact with atmospheric CO(2) and N availability. Soil temperature effects were confirmed for most of the variables measured and 3-factor interactions were observed for root development, plant biomass components, N-use efficiency, and shoot P content. Importantly, the soil temperature effects were manifest in the absence of any change in air temperature. Changes in root development, nutrient uptake and nutrient-use efficiencies were interpreted as counterbalancing mechanisms for meeting nutrient requirements for plant growth in each situation. Most variables responded to an increase in resource availability in the order: N supply >soil temperature >CO(2).     

气候变化对我国华北地区冬小麦发育和产量的影响

验证作物模型在我国华北冬小麦主产区是否适应的基础上,采用作物模型与气候模式相结合的研究方法,定量化地模拟预测了未来100年气候变化对华北冬小麦生产的影响.结果表明,从2000～2004年,华北地区冬小麦产量的模拟值与实测值的变化趋势基本一致,且生育期和产量变化不大.未来100年内华北地区冬小麦的生长期可能会有所缩短,平均缩短8.4 d;产量也会有不同程度的下降,平均减产10.1％.适当采取应对措施可以有效降低冬小麦的减产趋势.     

水分亏缺和施氮对冬小麦生长及氮素吸收的影响

利用管栽试验研究了不同生育期,水分亏缺和施氮对冬小麦生长及氮素吸收的影响.结果表明：任何生育期水分亏缺都会影响冬小麦的株高、叶面积、干物质累积及对氮素的吸收.冬小麦对水分亏缺的敏感期为拔节期,其次为开花期、灌浆期和苗期.苗期干旱后复水对后期生长有显著的补偿效应,开花期适度干旱后复水对生物量形成和氮素吸收有一定的补偿作用,拔节期干旱对小麦的生长影响明显.相同氮肥处理下, 与不亏水处理比较, 苗期水分亏缺、拔节期水分亏缺、开花期水分亏缺、灌浆期水分亏缺的根系氮素积累量分别平均降低25.82%、55.68%、46.14%和16.34%,地上部氮素积累量分别平均降低33.37%、51.71%、27.01%和2.60%.在相同水分处理下冬小麦含氮量、累积吸收氮量都表现为高氮处理（0.3 g N·kg^-1FM）>中氮处理（0.2 g N·kg^-1FM）>低氮处理（0.1 g N·kg^-1FM）.水分逆境条件下施用氮肥对冬小麦植株生长和干物质累积及氮吸收具有明显的调节效应.     

Heterogeneous distribution of phosphorus and potassium in soil influences wheat growth and nutrient uptake

Heterogeneous distribution of mineral nutrients in soil profiles is a norm in agricultural lands, but its influence on nutrient uptake and crop growth is poorly documented. In this study, we examined the effects of varying phosphorus (P) and potassium (K) distribution on plant growth and nutrient uptake by wheat (Triticum aestivum L.) grown in a layered or split soil culture in glasshouse conditions. In the layered pot system the upper soil was supplied with P and either kept watered or allowed to dry or left P-deficient but watered, whereas the lower soil was watered and fertilised with K. Greater reductions in shoot growth, root length and dry weight in the upper soil layer occurred in −P/wet than in +P/dry upper soil treatment. Shoot P concentration and total P content were reduced by P deficiency but not by upper soil drying. Genotypic responses showed that K-efficient cv. Nyabing grew better and took up more P and K than K-inefficient cv. Gutha in well-watered condition, but the differences decreased when the upper soil layer was dry. In the split-root system, shoot dry weight and shoot P and K contents were similar when P and K were applied together in one compartment or separated into two compartments. In comparison, root growth was stimulated and plants took up more P and K in the treatment with the two nutrients supplied together compared with the treatment in which the two nutrients were separated. Roots proliferated in the compartment applied with either P or K at the expense of root growth in the adjoining compartment with neither P nor K. Heterogeneous nutrient distribution has a direct decreasing effect on root growth in deficient patches, and nutrient redistribution within the plant is unlikely to meet the demand of roots grown in such patches.     

根区水肥空间耦合对冬小麦生长及产量的影响

利用管栽试验研究了根区不同湿润方式（整体湿润、上湿下干、上干下湿）、施肥方式（整体施肥、上层施肥、下层施肥）及其耦合对冬小麦不同生育期生长及产量的影响.结果表明：下层施肥方式显著降低了分蘖期冬小麦的株高和叶面积,而不同湿润方式对分蘖期株高和叶面积的影响不显著,拔节期水肥同区方式的株高大于水肥异区方式,表现出协同耦合效应.上干下湿方式和下层施肥方式显著降低了根系干物质量、地上部干物质量和总干物质量,上层施肥方式有利于增加冬小麦生物量,而上湿下干方式与施肥处理对地上部干物质量和总干物质量的耦合效应明显.水肥同区处理的根冠比高于水肥异区处理;上干下湿方式的水分利用效率显著高于整体湿润和上湿下干方式,水肥同区处理的水分利用效率高于水肥异区处理,但下层施肥方式的水分利用效率较低.与上干下湿方式相比,上湿下干和整体湿润方式的冬小麦单穗粒数分别增加了41.7%和61.9%,上层施肥和整体施肥方式的单穗粒数高于下层施肥方式,上湿下干方式与施肥处理对小麦产量及产量构成因素（除千粒重外）的水肥耦合效应明显.不同水肥处理主要通过影响单穗粒数来影响冬小麦产量.     

The effect of rhizoctonia root disease and applied nitrogen on growth,nitrogen uptake and nutrient concentrations in spring wheat

Root disease caused by Rhizoctonia solani is a common problem of spring wheat in South Australia. There are reports that nitrogen applications can reduce the incidence and severity of the disease. A glasshouse trail in pots examined the effects of disease and of applied nitrogen on wheat growth, and evaluated the utility of the basal stem nitrate concentration in diagnosing deficiency in plants with and without root disease. Plants were harvested at the mid-tillering stage. Shoot growth was increased by applied nitrogen until a maximum yield was attained, after which additional N had no effect on shoot yield. Root growth, however, responded positively only to low levels of applied N, after which it declined, and in the highest N treatment root mass was less than in the plants without applied N. Root disease caused severe reductions in plant growth, and both root and shoot mass were affected similarly. Even though growth of diseased plants responded positively to applied nitrogen the response was less than that of disease-free plants. The critical concentration of basal stem nitrate-N did not appear to be affected by root disease, and was estimated at 1200 mg kg^-1, consistent with other glasshouse data. The basal stem nitrate-N concentration, either in fresh or dried tissue, appeared a better diagnostic tool of N stress than did total shoot N concentration or content, because of sharper definition of critical concentrations. Concentrations of other nutrients in shoot tissue were affected differentially by both applied nitrogen and root disease, but generally did not reach critical levels, although phosphorus and magnesium appeared deficient in very disease-stressed plants.     

极端晚播对小麦籽粒产量、氮素吸收利用和籽粒蛋白质含量的影响

为探索小麦高产高效优质生产技术途径,指导小麦晚播生产实践,2012年10月—2014年6月,以弱春性小麦偃展4110和半冬性小麦矮抗58为材料进行连续2年的田间定位试验,设置了常规适播(10月中旬、240万株·hm^-2)和极端晚播(11月中旬、600万株·hm^-2)两种栽培模式,研究了极端晚播对0～40 cm土层土壤硝态氮含量、小麦氮素吸收利用、产量、籽粒蛋白质含量和氮素吸收效率的影响.结果表明: 与常规适播处理相比,两个生长季极端晚播处理均使拔节和开花期0～40 cm土壤硝态氮含量显著提高,从而促进拔节后小麦植株氮素吸收积累,成熟期穗部氮素的分配比例也得到提高,最终显著提高小麦籽粒蛋白质含量和偃展4110的蛋白质产量、氮素吸收效率,但对籽粒产量的影响因品种而异.其中,极端晚播处理使偃展4110的籽粒产量显著提高,而矮抗58的籽粒产量却显著降低.因此,极端晚播栽培模式可维持小麦拔节后的土壤氮供应,有利于提高小麦氮素吸收效率,从而提高小麦籽粒产量和蛋白质含量,是灌区小麦高产优质的有效途径之一.     

磷肥施用方式及类型对冬小麦产量和磷素吸收的影响

采用田间微区试验研究不同磷肥施用方式和种类对冬小麦生长和当季磷素吸收的影响.磷肥种类为磷酸二氢钙(MCP)和磷酸氢二铵(DAP),施用方式包括表面撒施,种子正下方5 cm条施,种子下方5 cm、偏3 cm条施,种子下方5 cm、偏10 cm条施,种子正下方20%土体混施5种.结果表明: 种子正下方5 cm条施对小麦的增产效果最高,其中磷酸二氢钙的产量达到7.63 t·hm^-2,磷酸氢二铵的产量达到7.99 t·hm^-2,分别较农民习惯撒施方式增产10.3%和10.7%.在5种施磷方式中,偏10 cm条施的小麦产量最低(6.60～6.77 t·hm^-2).种子正下方5 cm条施和20%土体混施处理的小麦总吸磷量均处于较高水平(34.4～35.6 kg·hm^-2),偏10 cm条施在小麦各生长阶段的吸磷量均显著低于其他施磷方式,但磷酸氢二铵偏10 cm条施的小麦总吸磷量较磷酸二氢钙高11.9%.表明将磷肥近距离集中施用于种子附近为该地区较为合理的施磷方式,在偏远距离条施下磷酸氢二铵对小麦的磷素吸收利用效果优于磷酸二氢钙.     

耕作播种方式对稻茬小麦生长和养分吸收利用的影响

2016—2018年,在四川省广汉市分析了深旋耕播种(DRT)、浅旋耕播种(SRT)和免耕带旋播种(NT)3种耕播方式对稻茬小麦生长和养分吸收利用的影响。结果表明:与DRT相比,SRT和NT处理提高了小麦分蘖、成穗能力。2016—2017年,处理间产量无显著差异;2017—2018年,NT处理产量显著高于DRT,增幅10.9%。处理间干物质积累的差异主要在苗期。NT处理下植株对氮的吸收量高于DRT,平均增幅9.9%,而氮收获指数DRT高于NT;各处理植株磷吸收量差异不显著;NT处理对钾的吸收量显著高于DRT。与传统的深旋耕播种方式相比,免耕带旋播种技术是提高稻茬小麦产量和养分吸收的有效途径。     

水氮处理对冬小麦生长、产量和水氮利用效率的影响

采用完全随机裂区设计,研究不同灌水(0、900、1200、1500 m³·hm^-2)和施氮(0、90、150、210、270 kg·hm^-2)处理对田间冬小麦生长、产量和水氮利用效率的影响.结果表明：冬小麦籽粒产量、氮素吸收量、氮肥利用效率和氮肥生产效率均随灌水量的增加而增加;氮肥利用效率和生产效率均随施氮量的增加而降低;施氮量在0~150 kg·hm^-2时,冬小麦籽粒产量、氮吸收量和氮收获指数随施氮量增加而增加,超过150 kg·hm^-2时不再显著增加;随灌水量的增加,冬小麦耗水量和整体水分利用效率增加,降水和土壤供水量占耗水量的比例及灌溉水利用效率降低;随施氮量的增加,降水和灌水量占耗水量的比例降低,土壤供水占耗水量的比例增加,整体水分利用效率和灌溉水利用效率先增加后降低,且均在施氮150、210和270 kg·hm^-2处理间无显著差异.综合考虑各因素,本试验条件下,生育期灌水1500 m³·hm^-2、施氮150 kg·hm^-2的处理为产量和效益兼优的最佳水氮组合.     

Effects of herbicide chlorsulfuron on growth and nutrient uptake parameters of wheat genotypes differing in Zn-efficiency

Prunings of Calliandra calothyrsus, Grevillea robusta, Leucaena diversifolia and farm yard manure were applied each cropping season at 3 and 6 t dry matter ha⁻¹ to an Oxisol in Burundi. The field plots also received basal applications of nitrogen (N), phosphorus (P) and potassium (K). Application of the tree prunings or farm yard manure decreased the concentration of monomeric inorganic aluminium (Al) in soil solution from 2.92 mg Al dm⁻³ in the control plots to 0.75 mg Al dm⁻³ in the plots receiving 6 t ha⁻¹ Calliandra prunings. The other organic materials also decreased the concentration of monomeric inorganic aluminium in the soil solution. The lowered Al concentration led to a corresponding decrease in the percentage Al saturation of the 0–10 cm soil layer from 80% to 68%. Grain yields of maize and beans were strongly inversely related to the percentage Al saturation of the soil. This confirms that soil acidity was the main constraint to maize and beans production. The yield improvement was mainly attributed to the ameliorating effects of the organic matter application on Al toxicity. The nutrient content had less effect presumably because of fertilizer use. In the best treatments, the yield of maize increased from 0.9 to 2.2 t ha⁻¹ and the corresponding beans yield increased from 0.2 to 1.2 t ha⁻¹. A C Borstlap Section editor